This open-label, multi-center, three-period, one sequence study will investigate the effect of ketoconazole on the pharmacokinetics of vemurafenib in patients with unresectable BRAFV600-mutation positive metastatic melanoma or other malignant tumor type that harbors a V600-activating mutation of BRAF without acceptable standard treatment options. Patients will receive a single dose of vemurafenib in Periods A and C and multiple doses of ketoconazole in Periods B and C. Eligible patients will have the option to continue treatment with vemurafenib as part of an extension study (NCT01739764). The anticipated time on study treatment is approximately 19 days.